This invention relates data to communication networks in which the bandwidth reserved for or utilised by a call can vary during the call.
The invention may be applied broadly in networks providing a continuous flow of traffic of controllable bandwidth. The network may be asynchronous, data traffic being allowed to be transmitted in a bursty manner but having an xe2x80x9ceffective bandwidthxe2x80x9d reserved for it. In an alternative, the network may be an nxc3x9764 kbits/s synchronous network where n can be varied to vary bandwidth.
The background to the invention will be explained in relation to a particular problem in one example of an asynchronous network, which is an Asynchronous Transfer Mode (ATM) network.
Although it is conventional to design non-blocking networks for telephone traffic and for narrow band data communication networks, a non-blocking network for broadband data networks would not be easily affordable. Given that from time to time, parts of a broadband network will become congested, a decision has to be made as to what to do on that occurrence. One option would be merely to refuse new calls. That used to be the practice in telephone networks. In today""s packet switching networks, new messages are not excluded, but congestion leads to delays in transmission of packets to the network and further delays in transmitting packets through the network. This produces a reduction in bandwidth, eventually packets arriving in the wrong order because they have used different routes, and ultimately loss of packets.
Another alternative, for which standards exist, is to control the bandwidth using the available bit rate (ABR) protocol. Each sending application places resource management cells into the outgoing virtual circuit in addition to the conventional data cells. The resource management cells contain rate control information and are returned via a return virtual circuit to the sender. The network nodes monitor their own utilisation and in the event of congestion or some other inability to deal with the rate demanded by the resource management cells process them to indicate a lower rate. On receipt of the amended resource management cells, the sending application is contracted to reduce the rate to that specified in the amended cells.
European Patent Application 0526118 A2 to Motorola discloses a communication system which dynamically calculates a call rate between two callers which is dependent on the system loading. The rate is transmitted to the callers who can choose to terminate the call if the call rate increases, and re-establish the call when the rate falls.
U.S. patent application Ser. No. 5,420,914 to Blumhardt discloses a method and system for real time selection of inter-exchange telephone carriers for a telephone call, and is designed to select the cheapest carrier and route for a call for the given time of day.
U.S. patent application Ser. No. 5,148,474 to Haralambopoulos discloses an interactive telecommunication system including automatic billing which allows a user to verify a call including the rate before establishing it.
U.S. patent application Ser. No. 5,065,393 to Sibbit discloses a system for controlling the cross-connect fields of a multi-locational switch network from a single location and to monitor reserved call time for each user on a link-by-link as well as link duration basis.
In inventive system, all applications are treated equally. The invention is based on the recognition that equal treatment may not make the most effective use of the network in the sense that for some of the calls, bandwidth and short delay will be more important to the users than for others.
Against this background, there is provided a network for carrying variable bandwidth calls between entities and comprising a network resource which generates charges, said resource comprising means arranged to determine dynamically the charging rate for its use dependent on call bandwidth and total resource utilisation or congestion, and to transmit the charging rate or tariff data representing an actual, proposed or change in the charging rate through the network to the entity liable to the resource for the charges, and wherein said entity is arranged to change the bandwidth of a call in response to a change in the actual or proposed charge rate in accordance with predetermined connection and charging rate criteria.
In a preferred arrangement the network includes at least one resource in the form of a domain containing at least one transmission or switching element, and for which the share comprises bandwidth or bit rate.
When the network is congested, the invention enables it to operate more effectively in the sense that a higher proportion of the calls will have a high value to their user.
The charging rate or tariff may in some cases not result in the exchange of money or money""s worth but could be used in, say a private, network, for internal audit or control purposes. In this case, the managers of the private network could, for instance, issue xe2x80x9ctokensxe2x80x9d to users shared out according to any priority scheme they wished. The users would use the tokens in a similar manner to using money to regulate their use of the communication system.
A domain in the network is a group of one or more network elements which generate charges for their use. Thus a call transmitted through some of the network elements of a domain will attract charges. It is proposed that the customers for whom wide bandwidth is more important may be willing to pay extra for it, while those for whom wide bandwidth is less important may prefer to reduce their bandwidth requirements so as to avoid extra payment or reduce their costs. The entity to which the tariff data is transmitted may be an end network element, if the domain is a local access network, or may be another domain. The tariff data may be altered at any time in response to commercial conditions and/or congestion in the domain, for example the price can be increased until congestion is controlled or merely to obtain the highest revenue for the domain.
Whether a domain passes the received call charges on to its own customer may depend on a managerial business decision. In one form of the invention, the tariff depends selectively also on charging rate or tariff data received from another domain.
The dynamic variation in the charging rate or tariff enables domains to compete with one another for traffic. To this end, the elements or domains are preferably able to select between alternative routes through the network, dependent on the charging rate or tariff data received from other network domains involved in transporting and providing services to the call.
In order for the ultimate customer to be able to make a decision, the network element liable for the call charges, may include an arrangement for displaying;
(a) the charging rate or tariff indicated respectively by the received charging rate or tariff data, or
(b) the charging rate determined by, the tariff data.
The network element or elements liable for the call charges may additionally or alternatively include control means to control the transmission bandwidth of a call until the charging rate indicated by the received charging rate data, or the charging rate determined by the received tariff data, is equal to or less than a value determined by a set of predetermined criteria. Preferably the network element includes an arrangement for selecting different predetermined criteria. The network element also preferably includes means to override the control means selectively.
For each end network element there is preferably stored a class of service indicator, a local access network being arranged to determine the tariff dependent also on the class of service indicator. A user paying a low basic service fee (e.g. line rental) would be allocated a low class of service indicator and may have to pay premium charges for a high bandwidth call, at a lower level of congestion than would a user paying a higher line rental and who would be allocated a higher class of service indicator. Alternatively or additionally, the user having the lower class of service indicator may have to pay a higher premium for a high bandwidth call at the same level of congestion.
Thus the local access network may be arranged to calculate a utilisation indicator representing its own utilisation and wherein the tariff determination sets the charging rate to a value of zero when a combination of the value of the utilisation indicator and the value of the charging rate indicated by the received charging rate data, or determined by the received tariff data, is less than a level determined by the class of service indicator.
More generally, the network may include at least one resource in the form of a data processor, and for which the share comprises processor time slots.
The network may include at least one resource in the form of data storage, and for which the share of total domain utilisation of a call comprises volume of data.
The network may include at least one resource comprising a sales outlet for goods and/or service items in which each good or service item is offered for a set price, and in which the good or service item is paid for through the network by the purchaser accepting a high charging rate for a limited period.
The invention extends to a method of operating a network to carry variable bandwidth calls between entities, wherein network resources which generate charges dependent on call bandwidth and total resource utilisation or congestion, determine the charging rate for their use dynamically, and wherein charging rate or tariff data representing an actual proposed or change in the charging rate is transmitted through the network to the entity liable to the resource for the charges, and wherein said entity changes the bandwidth of the call in response to a change in the actual or proposed charging rate in accordance with predetermined connection and charging rate criteria.